


One Punch Shirou

by Sir_Godot



Category: Fate/stay night (Visual Novel), ワンパンマン | One-Punch Man
Genre: F/M
Language: English
Status: Completed
Published: 2016-09-13
Updated: 2016-09-13
Packaged: 2018-08-14 21:36:05
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 12,961
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8029693
Author URL: https://archiveofourown.org/users/Sir_Godot/pseuds/Sir_Godot
Summary: [One-Shot] x [One-Shot] Shirou Emiya - an ordinary boy who wants to be a hero. And to be a hero, one needs to be strong enough to save the people in need. However, when you are literally strong enough to win every battle with one punch, you notice that it's not quite as grand as it sounds... Now with additional Servant Puncher version! [FSN x One Punch-Man Crossover]





	1. Chapter 1

**Author's Note:**

> Hey guys, welcome to my first one-shot in a looooong time. What can I say, I was busy and my muse was on vacation. This one-shot is something like a testversion of a fanfiction I'm currently working on. The stories involved will be the same, but the plot will be much longer and deeper.
> 
> The basic idea of this story was giving Shirou a power-up, and I thought: there are so many who overpower him, so why not write a story where it shows what the problem with too powerful characters is? And that's how this crossover with One Punch Man was born. If you don't know the manga, look it up, you're missing out on something, really.
> 
> But enough of that. Please enjoy the story.

"We interrupt our current program for an emergency broadcast! Several nearby cities have already been attacked and the source of this disaster is currently headed for Fuyuki City! I repeat, it is currently heading for Fuyuki City. Civilians are advised to immediately seek shelter and – "

At this point the lone person listening to the news turned the television off. He got on his feet and smoothed over his clothes before he headed towards the door.

There was work to do.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

Screams of terror. Sounds of explosions. A cacophony of despair echoed across the now destroyed cities Altrouge Brunestud had passed. The young looking Dead Apostle Ancestor was sitting on the back of her most faithful servant, Primate Murder. The impossibly large white beast was the source of the destruction around them, having mercilessly crushed men, women and children along with everything else in its path.

With a condescending sneer Altrouge gazed upon the destruction that had been caused on her orders. "Pathetic humans… and to think they believe themselves to be the dominant species of this planet. I have tolerated their insolence long enough, it is time to change things. Don't you agree, Murder?"

[Primate Murder – Disaster Level: God]

The Beast of Gaia gave what may have been an appreciative gruff, but only sounded like a sound from one's worst nightmare to all the people unfortunate enough to be still near it. As the demonic dog let its gaze wander, it noticed that there was one human, a young female child, which had apparently been lucky enough to survive the destruction it had caused. The girl was crying and trapped under some debris. It was an image that would have awakened pity in anyone – anyone who could feel something like pity anyway.

While Primate Murder didn't think like human species did, what went through its head was similar to "Well, that can be changed easily enough". It raised its massive paw and slammed it into the ground where the girl had been trapped, the impact resounding like an explosion and throwing up dirt and ashes. When it removed its paw to show its master its work, both the beast and the Dead Apostle Ancestor were in for a surprise.

The debris had been destroyed, but there was no trace left of the girl. Altrouge knew her pet's attack had been strong, but as it had been only playing around it shouldn't have annihilated the body like that. Oh, Primate Murder was perfectly capable of that and more, but something was off.

Suddenly the two noticed a new presence. When they turned their heads in tandem they saw the girl they had just attacked along with her apparent savior.

If Altrouge were asked to describe anything outstanding about him, she would have mentioned his white hair. The rest was… plain. He was pretty normal looking, a little taller than most people but not dwarfing anyone. He wore what looked like a simple black shirt with long sleeves along with equally black pants. And was that… yes, apparently he also had a red cape around his shoulders for whatever reason.

Still, he had managed to save a girl from an attack of Primate Murder, no matter how lackluster it had been.

"Who are you?" She asked, completely unfazed. She knew he was going to die, but maybe this would make things a tad more interesting.

The figure gently sat down the by now unconscious girl before he slowly but confidently walked towards the vampire and her demonic servant.

"Just an ordinary guy who works as an ally of justice." The newcomer said as if he wasn't standing before an incarnation solely created to eradicate humanity.

Altrouge had to blink at the sheer gall of the human in front of her before she started scowling. "I don't like your tone… Actually, I believe you're mocking me. An ally of justice? Did you watch too many kids' shows when you were young?"

Something about this guy irked Altrouge. She didn't like being irked. At all. Things that irked her were pretty much doomed to end up as interestingly shaped stains on the floor. "Do you even know who you just challenged? I am Altrouge Brunestud, the descendant of Crimson Moon himself! With Primate Murder on my side I am a being that even surpasses the Ultimate One of the Moon! The True Ancestors were created to save the Earth from humanity, which is nothing more than a parasite that is slowly killing the planet! We have waited long enough for this day, it is time to purge the Earth and begin a new age! You have no idea what you got yourself into."

After her outburst, the young looking vampire calmed down again while the self-proclaimed ally of justice just looked at the two with a blank expression. "Oh well, it doesn't matter. You're dead anyway. Primate Murder? Show him how you earned your name."

The white beast was only too eager to obey its master's command. Impossibly large muscles bulged and tensed as the white beast prepared to attack its "opponent". Of course, to Primate Murder there was no equal on this world except maybe the foreign beings from other planets, like ORT, the Ultimate One of Mercury.

So after not even a split-second of preparation, the white beast descended upon its opponent with its claws and fangs. The battle had already been over when the human had entered its range, for at this point nothing could stop its fully focused atta –

And then the head and upper body of Primate Murder turned into a fine red mist, courtesy of the single punch the caped man had thrown.

The rest of the beast's body fell to the ground and didn't move, which wasn't surprising as it lacked approximately 80% of its vital organs, primarily its head. Altrouge, who had been sitting on the creatures back, had slid down when it had fallen over and was now sitting in a constantly larger growing puddle of blood. Her eyes were wide open and her mouth was opening and closing, but no sound came out. She was incapable of putting her thoughts in words – not like there was much going on inside her head aside from the word "what" echoing through it again and again.

The black garbed ally of justice just stared at his fist with an unreadable expression. His gaze shifted back to the carcass of the Beast of Gaia, then to his fist again.

"FFFFUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUC K!"

Truly, the life of Shirou Emiya was wrought with peril.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

Let us go back a bit further in time to see how the things that just transpired came to be.

Ten years ago, Shirou Emiya had been born. While something like a birth is not too uncommon, being around 8 years old when it happens is a bit on the unusual side.

Shirou Emiya was born in the aftermath of a magical ritual known as the Holy Grail War. Seven magi summoned seven Heroic Spirits to fight for the Holy Grail, an artifact with the power to grant any wish. But as it is often the case with great power, things NEVER go as planned. It turned out the Grail had been corrupted in the last war, and when the winner of the fourth war had tried to destroy the Grail in order to stop it from bringing death and destruction to the world… well, exactly those things happened, only on a smaller scale.

Shirou Emiya had survived the fire that the Grail had thrown at the world as its last act before returning to a sleep-like state. The very man who had accidentally caused the fire by destroying the Grail, Kiritsugu Emiya, had managed to save a single child from the fire and consequently adopted him – Shirou Emiya.

Being saved from the brink of death by a man with indescribable happiness on his face caused one thing in the child: the wish to be as happy as the man who had just saved him. And when the man who would become his adoptive father told him that he had always wanted to be a hero who could save everyone, it really stuck with Shirou.

Now, while Shirou wanted to save everyone, he knew that this was no easy task. If it was easy, people would already do it on a regular basis. No, to become a hero he had to be strong. Strong enough to defeat anyone who threatened another, fast enough to be where his help was needed, tough enough to withstand anything thrown at him. For a child as driven as Shirou, there was only one way to accomplish this monumental task.

Training.

After two years of feeling his bones creak, spitting blood and being constantly in pain, Shirou noticed two things.

One, his hair had turned completely white.

Two, he had become strong enough to crush anything with a single punch.

At first Shirou had been ecstatic about this discovery. While his hair garnered him some strange looks, it was a price he was glad to pay as long as he could now save everyone in need. So the now white-haired teenager set out to make the world a better place. He fought monsters, averted disasters and stopped ordinary humans from harming each other. And for a while everything was good for the young man. However, after a few weeks of working as an ally of justice, he noticed a third thing.

It was incredibly boring to be strong enough to beat anyone with a single punch.

No matter how terrifying the opponent, no matter how massive they were, everyone was felled by just a single punch, just like Primate Murder had been reduced to a bloody puddle after being hit only once.

Although he knew he shouldn't wish for any conflict or threats, Shirou couldn't help but wonder what it would be like to fight against someone who could push him to his limits.

And now, ten years later, the Holy Grail stirred again.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

Rin Tohsaka was not in a good mood. The last few days had been beyond stressful with the Command Spells marking her as a Master of the Fifth Holy Grail War appearing recently much to her surprise. Not only was the war about 50 years early, but the entire city was in a frenzy. Apparently a large white dog had been rampaging through the area two days ago before dying a mysterious death. She was glad it had not reached Fuyuki City as dealing with something like that would have brought her a particularly nasty headache for sure. When she had first heard of the description she had thought the legendary Beast of Gaia, Primate Murder, had been headed for her city, but when she had heard of its demise those thoughts had disappeared completely. After all, what could possibly stop a monster like that in its tracks? Therefore it had probably been a similar beast but clearly inferior when compared to the legendary white beast.

Another source of stress was currently sitting in the church of Fuyuki City, and for once Rin was not referring to her much loathed guardian Kirei Kotomine. No, the problem was that a vampire had taken up residence in the church, a very powerful one at that. She hadn't said it out loud, but she had been cackling inwardly when Kirei had admitted that him trying to oust or exorcise the vampire would only lead to him being a particular stain on the church carpet. Luckily for both of them, the vampire seemed to be in a sort of trance as all she did was sit on the church banks and silently mouth the word "what" over and over again. Well, no one had said vampires were known for being sane. Still, it was a situation that had to be observed carefully.

The last problem was currently accompanying her. After her Command Spells had appeared, Rin had poured everything she had into the summoning of her Servant. Her long hours of hard work had been awarded with the appearance of Saber, the strongest of the three Knight Classes. Unfortunately her Servant had a problem with astralizing, so she was constantly visible and unable to hide from view like other Servants could. While she had managed to get Saber to wear one of her spare uniforms so she wouldn't stick out like a sore thumb, she was still constantly accompanied by the girl. It made scouting for other Masters a lot harder than it could have been.

So a few minutes later her last problem came to an abrupt end when the evening calm was suddenly interrupted by the appearance of a small girl with long white hair. She looked completely innocent, like a little princess straight out of a fairytale. If not for the eight feet wall of walking muscle behind her, people would have believed her unable to harm a single fly.

"Hello, onee-chan. My name is Illyasviel von Einzbern. I was looking for someone else, but as you have your Servant with you I thought 'why waste the chance?'. It's a shame you'll drop out already, but that's life. Berserker, kill them."

The order was spoken without malice and childlike innocence, but the result couldn't have been further from that.

With a shout of "Rin, stay back!", Saber rushed past her Master and engaged the monstrous Servant in combat. It was a battle beyond human understanding as several blows were exchanged in the blink of an eye and the ground was ripped apart and shattered from the forces affecting it. To Rin's relief Saber was capable of holding up against the terrifying Berserker, whose presence gnawed at her senses to run away and hide. However, her Servant remained steadfast, so they still had a chance to win this battle!

"Hmm, I should really buy some vegetables tomorrow; these prices are really good..."

And with that the tense atmosphere was completely shattered. With incredulous looks Rin, Illya and even Saber stared at the new figure that had stumbled across their battle. The twin-tailed magus immediately recognized the newcomer as her schoolmate Emiya, as his hair was rather unique and still a popular topic at school. Dread gripped her heart. She had tried to keep everything about magic a secret to the people around her, and now, because of a stupid coincidence, the boy would die. It didn't matter if she tried to save him, there was no way Saber could defend both her and Shirou from Berserker. Rin clenched her fist angrily as her mind raced to come up with a solution for the problem, but the chances were slim.

Illya was also surprised. From the photos her servants had acquired for her, she could tell that this was her elusive "brother", the boy Kiritsugu had adopted in favor of her. What a lucky coincidence! This evening was getting better and better. A smile appeared on Illya's face, but this one was everything but innocent.

"Berserker, change of plans. Kill onii-chan first. Crush him to a pulp but leave the head intact!"

Shirou was slightly confused. Here he was on his way back home after yet another patrol around the city, and something really strange was happening. The school idol Rin Tohsaka and another girl in armor were fighting a little girl and what looked like the result of someone trying to see just how muscular someone could get. And now the little girl had sent the walking pile of muscles and rage after her.

'And this still doesn't rank among my Top Ten Weird Events. Maybe I should start looking for a therapist…'

Just when it seemed like Illya's grin couldn't get any wider, Shirou decided to solve this situation like he solved any situation:

He punched the problem.

The grin remained firmly on Illya's face, even as Berserker turned into a fine red mist. Only his legs were still standing where the Servant had once been, like the remains of a statue someone had dug out. Upon closer inspection one would also notice that the grin on Illya's face seemed somewhat frozen, as if she was only still grinning because she had forgotten to change her facial expression. Then the three girls blinked. Even Berserker would have blinked in confusion had his eyes and head not been turned into a spray of blood a few seconds ago.

"… What just happened?" Rin asked more in general than anyone specific, not really grasping what had just transpired.

"… I have no idea." Saber admitted, though she eyed the white-haired boy warily.

Finally, Illya recovered from her shock, but it was clear she was still shaken. "I-I don't know what happened, but it doesn't matter! Berserker has twelve lives, so he will just come back again! Your tricks won't work twice on him, onii-chan!"

Shirou was still not quite sure what was going on, but he could see that the hulking pile of muscle called Berserker was indeed regenerating quickly. A few moments later the Servant was completely restored and snarled angrily at Shirou.

As the problem was apparently not solved yet, Shirou punched it again.

Berserker once again turned into tiny chunks of Servant, this time even his legs exploded from the impact.

The silence on the street was slowly turning awkward. It didn't help matters when Berserker angrily regenerated for the second time but was turned into minced meat not even a second later yet again.

By the fourth time Saber had lowered her sword, and when Berserker started his tenth regeneration, Rin took a look at her wristwatch to see when she'd probably get home. Illya on the other hand had started to develop a severe case of PTSD (Posttraumatic Shirou Disorder), and her mouth was now opening and closing without making a sound, although one could see she was silently mouthing the word "what" again and again.

"… and that's twelve." Shirou said as his last punch turned his opponent into particles. Shirou actually felt bad about doing it at the end because after the ninth punch even Berserker had started to look afraid. It hadn't stopped the mad Servant from attacking him, but the white-haired ally of justice had started to see something like resignation and fear in the rage-filled face of his opponent after a while.

And so Shirou once again saved the day. The fact that it had taken twelve punches instead of one only made him feel slightly better.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

After dropping off Illya at the church (next to the vampire who had somehow identified Illya as a fellow PTSD victim), Rin and Saber accompanied Shirou to his house to get some answers. To be fair, Rin was only slightly surprised to see her estranged sister Sakura at Shirou's house as she knew that the two were acquainted. It surprised her a hell lot more though to see Sakura opening the door wearing nothing but an apron and a smile that spoke of thoughts so dirty that any attempt to put them on paper would result in the paper spontaneously combusting.

"Good evening Sempai. Do you want a bath, dinner… or me?" Sakura spoke with a voice that only too clearly revealed what choice she was hoping for.

While Rin was trying to wrap her head around what she was seeing and silently wondering how Sakura hadn't noticed her and Saber yet, her Servant was developing a slight twitch in her right eye. However, both of them were even more shocked when Shirou took a step forward and proceeded to kiss the living daylights out of Sakura (ignoring that it was evening).

"Oh Sakura, you always know how to cheer me up." Shirou said as the two interrupted their impromptu make out session to breath. "I met another strange being today, and while it died after one punch it could regenerate, so it took twelve punches altogether."

"Oh Sempai," Sakura giggled as she hugged Shirou tightly, pressing her generous assets into Shirou (which caused Rin and Saber to feel inadequate). As the two watchers coughed to gain their attention, Sakura didn't really react as expected. She only shot Rin and Saber a glare that promised untold sufferings for interrupting her planned nookie time. "… I see you brought visitors Sempai."

Shirou scratched the back of his head awkwardly when he remembered that little tidbit. "Oh yeah, I ran into these two when I met the regenerating muscle thing. They said they had some questions."

"I bet they do…" Sakura muttered before turning around, ignoring the indignant squeaks from anyone but Shirou as she presented what her apron did not cover to the three people at the door. "I'll prepare some tea then."

When Sakura had vanished, Rin seriously considered strangling Shirou for whatever he had done to her little sister, fists with the power to one-hit kill Servants or not.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[A few minutes later…]

The group consisting of Rin, Saber, Shirou and a now clothed Sakura, was sitting around the dinner table in silence. It was clear that Sakura was still very cross for being interrupted earlier, and Rin and Saber were not quite sure how to address the topic. Shirou was simply smiling and patting Sakura's back in order to comfort her. It was probably the only thing stopping the purple haired girl from severely maiming the other girls at the table.

"So… Emiya…" Rin began slowly. "I guess I just cut straight to the point: what the hell are you?"

Shirou tilted his head. "I don't really understand what you mean. I'm a normal human."

"Bullshit!" Rin shouted, slamming her hands on the table. Saber remained composed, but her expression showed that she thought very much the same thing. "A normal human couldn't hope to even scratch a Servant! And you took out the strongest Servant in the entire Holy Grail War with punches! Punches! The world doesn't work like that!"

Shirou looked a bit confused at Rin's accusing tone. "But that's all I did. Well, I went through training from hell of course to get this strong, but it's nothing special, anyone could do the same. And it was really just a simple punch."

Rin's eye was developing a very unhealthy looking twitch, but was managing to keep herself under control. "Ok… so it is the result of your training. Well, I know the human body can be very malleable… So what was your training?"

The magus wouldn't admit it out loud, but she was actually quite curious what training would allow someone to gain enough power to crush a Servant with a simple punch and not even be strained by it. Saber was likewise interested in the way the young man had used to obtain a power that, frankly, made her feel a bit inadequate.

Shirou's expression turned serious. "Very well, I don't mind telling you. But keep in mind, you have to do this training daily for 3 years so you can notice its effect. I was in constant pain and throwing up blood after a while, but I powered through and gained this strength as a result."

He looked the Servant-Master pair straight in the eye. "100 push-ups, 100 sit-ups, 100 squats and running 10 kilometers. Every. Single. Day."

Silence followed. Then Rin slammed her hands on the table again. To everyone's surprise, Saber had done the same.

"Bullshit!" They shouted in tandem before Rin continued, ignoring Shirou's retort of "But that's all I did".

"There's no way you got this strong with a workout like that!" The twin-tailed magus then fixed her gaze on the remaining occupant of the room who had not yet said anything. "And you! What are you doing here, and why were you skipping around in the house naked when we came here?"

"I wasn't naked, I was wearing an apron. Silly Tohsaka-sempai."

"Not my point!" Rin continued. "Show some decency for crying out loud. I'm not saying you shouldn't do… whatever you do when there's no one around, but I don't think your family would like seeing you do things like that! … come to think of it, I haven't seen that idiot Shinji in a while…"

As Rin's tirade ended, Sakura began speaking. "Oh, nii-san and grandfather are on an extended vacation. They might not be back for years, if ever even." This statement was accompanied by a smile far too angelic to be true.

Rin and Saber looked at Shirou with a raised eyebrow, as if trying to get a sensible answer from him. The white haired boy interrupted his back-patting of Sakura to quickly smash his right fist into his other hand. A look of understanding and slight horror dawned on Rin and Saber's faces. The Tohsaka heir knew that Zouken was a very twisted individual and that close to being classified as a Dead Apostle by the church. Apparently the problem had been taken care of. Permanently.

"… a vacation." Rin repeated, as if baiting Sakura to admit what had really happened.

The smiling girl only nodded. "A vacation. For a veeery long time. That's why I moved in with Sempai, it was lonely at my old home. And because my therapist is closer that way."

Rin decided then and there that she wasn't going to touch that topic with a ten foot pole.

The magus tried to calm herself. "So Emiya, tell me. What do you know about the Holy Grail War?"

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[Two days later…]

Kotomine Kirei was not a man easily disturbed. Even if there was something that surprised him, he could easily remain calm and collected, finding the best solution for whatever problem he was dealing with. But even a man like him had to admit that his church getting fuller and fuller with apparently traumatized people was not something people had to deal with often.

On the one side he liked seeing so many people in obvious misery, but as they barely did anything but mouth the word "what", occasionally eating and drinking a bit before returning to this action, he found himself unable to make their lives even more miserable or even find happiness in their suffering as he didn't know the source of it. He did know however that it was connected to the Holy Grail War.

The first hint had been that his connection with Lancer had disappeared, the last and only thing he had seen before his Servant's demise had been a rapidly approaching fist that had filled the spearman's entire vision. Then there was Luviagelita Edelfelt, the magus who held a strong rivalry with Rin. The Master of Archer had boldly challenged Rin, who was apparently working on something with the adopted son of Kiritsugu Emiya, but the Edelfelt girl had soon returned to the church in the same condition as the vampire and the homunculus. And as he had also sensed the strange aura surrounding Ryudo Temple disappear; it was safe to assume that Assassin and Caster had also been vanquished. That only left Saber and Rider, the latter being an unknown in both identity and Master.

"Kirei!" Gilgamesh yelled angrily as he strode into the church. "Tell me what is going on! The Servants are dying like the flies most of them are, but there are no signs of battle. I would have noticed it had Saber managed to crush the competition. Even your dog was defeated easily. What do you plan to do now?"

Kirei knew when he had to placate the former king of Uruk, so he wisely chose a more active path for his future actions.

"My king, as there is apparently a considerable power in Fuyuki, it might be prudent for yourself to seek out the upstart before having your desired fight with Saber. After all, there are no more disruptions as the Rider has yet to show himself."

Gilgamesh's eyes narrowed as he considered the priest's words. "Very well… it seems the finale of this show is due sooner than expected… Maybe fate is merely wishing for its greatest actor to appear on the stage earlier…"

The incarnated Servant strode off for his desired battle with Saber, Kirei obediently following behind. It was time to show Rin and her little friends the true meaning of despair. And with the vessel for the Grail already in the church, there would be no further problems. Well, aside from the vampire possibly ripping them apart. But Kirei chose to push ignore that possibility to the back of his mind.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

With confident steps Gilgamesh approached the Emiya residence as if he owned it, which he actually did according to his own definition of being the absolute ruler of the world. However, when the King of Heroes arrived at the entrance to the house, he noticed that something felt off. While he was no expert of the mystic arts, he felt something more than just Saber's presence now that he was this close to the house. He ignored Kirei when the priest came to a stop next to him; instead he concentrated on the feeling that seemed like a memory just out of his grasp. His thoughts were interrupted when the inhabitants stormed out, having noticed him at the same time he had been able to sense them.

"Archer!" Saber shouted, her invisible sword firmly in her hands. Behind her Rin and Shirou appeared in the door, and while Rin had a fierce expression on her face, Shirou seemed somewhat bored.

"Kirei." The magus spoke, her eyes narrowing. "So my gut feeling was right… you did have more to do with the Holy Grail War than you let on."

A thin smile appeared on the priest's face. "Very good Rin. As your mentor I am proud you managed to deduce this much. I have to admit though, things did not go quite as I had predicted. It seems a power greater than an average Servant has taken an interest in the Holy Grail War. It made orchestrating things a bit more… tedious so to speak."

"I remember now." Gilgamesh suddenly spoke up. To Saber's great surprise he ignored her and instead focused his gaze on Shirou. "You, peasant. You have performed the Ancient Babylonian Workout, have you not? Your aura, your very presence screams of the power only possessed by those who managed to complete it."

"Ancient Babylonian Workout?" Shirou, Rin and Saber chorused, although in Saber and Rin's voice a hint of annoyance could be heard.

"Of course." Gilgamesh continued, even causing Kirei to raise an eyebrow. "In the ancient times when I first ruled the world it was mandatory for all warriors to undertake this training."

A serious expression appeared on the king's face. "The legendary training of performing 100 push-ups, 100 sit-ups, 100 squats and running 10 kilometers. Every. Single. Day."

The silence that followed was almost palpable, aside from the slight choking noises Rin was making.

Shirou nodded. "That's what I did. See Tohsaka, it IS a valid workout, even the golden guy knows that."

Rin wasn't sure whether she should try strangling Shirou or save herself the trouble and just bash her head against a wall. Judging from her facial expression, Saber was feeling the same way.

"However," Gilgamesh continued. "While my body is not in its prime, I shall challenge you to a contest of strength, peasant! Rejoice, for you have garnered my attention! Now, prepare yourse-"

And then Gilgamesh miraculously turned into a shower of chunky red parts.

Everyone turned their attention to Shirou, who was still standing in front of the former Heroic Spirit, his fist still hanging in mid-air.

"... what?" Shirou asked as he walked back to Saber and Rin. "He was talking too much. I have better things to do with my evenings, you know."

After this little display, the trio focused on Kirei, who suddenly felt very exposed.

"…" Kirei didn't blink as he stared at the group.

"…" The group remained silent as well, although Saber slowly raised her sword and Rin took out a gem. Shirou was wondering why the mullet guy was even here. The priest decided to perform one last attempt to escape the mortal danger he was in.

"… So, who's up for Mapo Tofu?"

They weren't the greatest last words ever spoken, but there were worse.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[A few days later…]

With a content sigh Shirou emptied his cup of tea, Sakura sitting at the other side of the table and mirroring the action. After the whole stuff with the priest had been dealt with, things had calmed down a lot. Rin had set out with Saber to look for Rider and his or her Master, following a lead about some guy trying to conquer the world with the help of a professor from the Clock Tower. It didn't really matter to Shirou as he had promised his big sister figure to finish school before setting out and being a hero worldwide. So for now he could relax and deal with the problems that always seemed to gravitate towards Fuyuki City.

Like right now, which resulted in his front door being obliterated. Shirou scowled a bit at that. The person responsible for that should better pay for that or he'd be really angry. Sakura merely sighed and stood up to get a broom. Some people really had no manners.

The one who had caused this then stepped into the living room. It was a young looking woman wearing a white sweater and a long purple skirt. Short blond hair framed her head and red eyes stared at him angrily. Shirou also noticed that a vaguely familiar girl with black hair was being carried by her under one arm.

"So," the blond woman began. "You're the one who did this to my sister I hear?"

With a sigh Shirou stood up. A hero's job was without end after all.


	2. Second Punch: Servant Edition

**Summary for the Chapter:**

> [One-Shot] x [One-Shot] Shirou Emiya - an ordinary boy who wants to be a hero. And to be a hero, one needs to be strong enough to save the people in need. However, when you are literally strong enough to win every battle with one punch, you notice that it's not quite as grand as it sounds... Now with additional Servant Puncher version! [FSN x One Punch-Man Crossover]

Here is my oath. I am the one who becomes all the good of the world of the dead, I am the one who lays out all the evil of the world of the dead.

You, seven heavens clad in three words of power, arrive from the ring of deterrence, O keeper of the balance ―――！

These words echoed throughout the basement of the Tousaka mansion as its owner and resident Tsundere, one Tousaka Rin, attempted to summon her Servant for the Holy Grail War. She had prepared everything painstakingly and was sure that she would summon the Heroic Spirit most suited to be her partner!

However, she really should have expected something to go wrong in a ritual that involved invoking the name of Zelretch, who was known far and wide as a man with a special kind of humor.

And something did go wrong indeed. Just as she finished the last word and the ritual began, the magic circle produced strange sparks and soon after caused an explosion of dust. As Rin was knocked over, she heard the sound of wood breaking above her. So naturally, once she had regained her bearings, she entered the living room and came face to face with her Servant, the one most suited to fight for her in the Holy Grail War.

Rin felt her eyebrow start to twitch as she saw a rather relaxed, white-haired individual wearing what looked like a cheap superhero outfit in black with a white cape sit on her couch. Well, it wasn't just the outfit that caused her to start developing a headache. No, the real problem was the utterly uncaring face of her Servant which he was currently stuffing with her favorite potato chips! She had been saving those all week, dammit!

Just as Rin was about to unleash a flood of very angry comments, her Servant looked up from his place among her destroyed furniture.

"Oh hey, it's Tousaka. How's it going?"

That comment stopped Rin dead in her tracks as she tried to process what she had just heard. After a moment of consideration, the genius witch found the appropriate reaction to her Servant, a legend summoned back to the world of the living, knowing her name.

"... what?"

Her Servant rolled his eyes. "Wow, you really were always like that. I asked how you're feeling. I'm kinda surprised I was summoned by you as a Servant."

'Tousaka Dot Exe has finished rebooting. Begin formulating actual answer.'

"Just to make sure we're on the same side here... You, a Servant, a soul summoned from the Throne of Heroes, know me?"

The white haired Servant raised an eyebrow. "Duh, of course I know you. We went to school together. Wait, no, are going, this is the past, right? Oh yeah, and I'm your brother-in-law, seeing how I married your sister. Will marry. Am going to have married? Damn this stuff is confusing."

To combat his time travel induced confusion, the Servant ate some more potato chips while Rin tried to make sense of what she had just learned.

"... you're a Heroic Spirit from the present? And we go to school together? Seriously?"

The mere thought seemed inconceivable; the number of people ascending to Heroic Spirits had steadily decreased over the centuries.

"Yeah, I just told you that." The caped man replied. "Don't you recognize me? I mean, sure, I look a little different, but we DID know each other before all of that happened. Or were at least aware of each other's existence, I think."

Rin decided to take a closer look at her Servant. She didn't know anybody with white hair at her school, but now that she stood in front of him she realized that he did seem somewhat familiar. However, she just couldn't recognize that bored expression of his.

"All right, I give up. Who are you?" Rin asked with a resigned sigh.

A deadpan stare was the first answer to her question. "Really? Wow, that kind of hurts, you know? It's me, Emiya Shirou."

A blank stare was all he got as response.

"... the red haired guy from Class 2C?"

The blank stare continued.

"The only 'friend' of Matou Shinji?"

"Shini has friends?!"

"The 'fake janitor'?"

And now, enlightenment.

Followed by a horrible realization.

"Wait, I summoned Homurahara's brownie as my Servant?!"

"Yes." Her Servant's short answer made Rin feel as if all her energy had been sucked out of her.

"... what kind of class could you possibly be summoned under? And in that kind of outfit?"

'Shirou' finished the bag of chips and answered with a completely calm voice. "It seems my class is 'Puncher'. Huh, funny that, not one I encountered in my past. Present. Damn this will stay confusing."

Rin's jaw dropped open. "Puncher? What kind of class is that?!"

"It's my class, I already told you that."

Just as Rin was about to finally start her tirade to vent her frustrations, something else finally caught up with her.

"Wait... you married my sister?!"

Puncher actually blushed a little when Rin said it out loud, before a smile appeared on his face. "Ah, yeah. What can I say, when she first did the 'naked apron' for me, I knew she was the one for me."

And then Rin tried to murder her own Servant.

All in all it was a very productive first meeting for the pair.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[The next day]

Rin had calmed down somewhat since her attempt to strangle her Servant with his own cape. The white haired hero had taken it with the same unimpressed stoicism he expressed most of the time, so no one had been hurt – except for Rin's pride.

And her pride was taking yet another beating as Rin found herself unable to actually see her Servant's stats. Sure, she could see his class name (and much to her dismay, it really was 'Puncher'), but everything else just showed her the equivalent of an error message.

However, Rin was nothing if not a true magus, and so she had used her resources to construct a device to amplify her Master vision. She had taken a red gem and changed its form into a flat 'screen' that was attached to a metal construction that Rin could fasten to her ear.

It did in fact look remarkably like a certain power level measuring device used in a well-known anime, but Puncher knew enough about Rin to keep that tidbit of information to himself.

"All right, now let's see what we've got."

With a press of a built-in button, the Mystic Code amplified Rin's ability to see the stats of a Servant. It worked as intended and immediately began to calculate her Servant's power levels.

Calculating... calculating... still calculating...

After 20 seconds of this Rin began to get a little worried she had made a mistake while building the device. However, that worry soon was replaced by shock and surprise as the Mystic Code began to emit smoke. The twin-tailed girl quickly threw it away with a squeak of surprise.

The moment it left her ear, it went up in flames.

As Rin saw the work of her last few hours go up in smoke, she briefly considered going back to the drawing board before deciding against it.

She was quite sure the last reading her Mystic Code had given her had been "Fuck this, I'm out!"...

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[Later that day, evening hours]

By now Rin had to work hard to keep the exasperated look from her face that had become some kind of default state for her ever since she had summoned her Servant. Puncher just plain out defied logic and common sense, both with his actions and his words. Becoming a hero capable of defeating anything with a single punch after a few years of core workout? Yeah, right...

Still, with the blue-clad Servant wielding a lance in front of them, Rin supposed that she would see the power of her Servant soon enough.

"... what the hell are you wearing?" Lancer asked after seeing Puncher.

"What's wrong with my outfit?" Puncher asked, already a little annoyed. He liked his hero outfit!

"Well, it looks ridiculous. Like you're imitating a comic book hero, and badly at that." The spearman clearly was more than happy to make fun of his next opponent.

"... coming from the man wearing a blue full-body condom, I think all criticism about my outfit rings hollow." Puncher countered drily.

Apparently, Lancer was not the type to take criticism well. "You know what? Fuck pre-battle banter, I'll just kill you now. So do me a favor and DIE!"

With the last word, Lancer rushed forward, using the incredible speed of his class to its fullest. Only a fraction of a second later he was already in front of Puncher, his spear now aiming at his opponent's heart –

And next thing Lancer knew, his danger senses screamed at him and it was a suddenly little drafty in his chest area. He quickly pulled back and inspected his upper body. He was finished quickly as it turned out that he no longer had a chest to check for injuries.

"... are you fucking kidding me?" Lancer asked as he started at Puncher incredulously.

Puncher himself raised an eyebrow while Rin did her best impression of a fish, her mouth opening and closing without a sound coming out.

"I'm kind of surprised you're still talking. I'm pretty sure I saw your heart flying away."

"I have A-ranked Battle Continuation, so with my last breath, let me just say, I call bullsh-"

And then Lancer fell over, dead.

Rin finally remembered that her species had spent millennia getting out of the water and thus did not need to imitate fishes. "... what the hell just happened."

Puncher sighed. "The same thing that always happens when I get into a fight... Seriously, were you listening when I told you about my training?"

Before Rin could answer to this in any way, both were interrupted by a wet sounding gurgle that came from further back.

Rin's Servant took a closer look with his enhanced senses and promptly looked a little embarrassed. "... oops."

When Rin and Puncher investigated the source of the sound, they found a certain red haired boy lying in a steadily growing puddle of blood. His chest was torn open and his heart visible, but judging from the stains on his shirt, Rin soon realized where Lancer's heart had gone after it had vacated its owner's ribcage.

"... you all but killed an innocent bystander with a Servant heart. And to top things off, it's your own past self. There is so much wrong about this situation, I don't even know where to start." Rin said with an emotionally dead voice.

"Wait, so if he's my past self... am I going to die too if he dies? Also, how can something like this even kill him, I was already this strong at your age... So is this a parallel timeline...? Damn, my head hurts from all this time travel stuff."

Rin ignored Puncher's complaints as she began to heal the boy lying in front of her. It had been her fault (indirectly) that he gotten hurt, so the least she could do was to preserve his faint but still present life.

Little did Rin know that this would only open yet another can of worms...

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[A little later...]

Emiya Shirou awoke with a groan and a massive headache. He vaguely remembered staying behind at school to fix some stuff. He then had heard people talking and wondered if someone else had stayed, or worse, if someone unauthorized had snuck on the school grounds. Shirou had then come across two weirdly dressed guys and one girl, and the next thing he knew, he had been knocked out.

"Did I just dream all of that?" Shirou wondered out loud.

"Believe me kiddo, I wish you did." A voice right next to Shirou answered.

"... who said that?" The fake janitor of the school did not like where this was going.

"I did."

Shirou turned around and came face to face with a ghostly silhouette of one of the men he had seen earlier, only now the man in blue was not carrying his spear.

"You know, this Holy Grail thing is becoming less and less of what I had hoped by the second."

The red haired boy next to Lancer naturally did what every person would do in such a situation.

He fainted.

"..." Lancer stared at the unconscious boy. "Oh yeah, I can already see how much fun this is going to be."

Lancer would have dragged the boy home if he knew where that was or if he could actually touch anything. As he couldn't do either, he sat down and prepared himself for a hopefully short waiting period.

"... I hate my life."

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[The next day]

Tousaka Rin was well known at her school for her looks, smarts and personality. Not many knew that the image of the perfect student was one she actually had carefully developed and not her real personality. Oh, she did look good and was smart, but the way she interacted with her fellow classmates did not really represent what she was like at home.

And never had that image been harder to maintain than at this very day.

Standing on the school roof, Rin looked like she hadn't slept all night, and the shadow under her eyes would make a panda comment on it. The reason for this was not that she had forgotten to go to bed or anything, oh no, she had done that. That had actually been the problem. For while Rin was unable to properly see her Servant's stats and abilities, she had seen his past in the 'dream cycle', which was both the result of entering a Master-Servant contract and meant to help the two understand each other better.

Only what Rin had seen had felt like an unending horror trip.

Puncher had fought everyone and everything that could even remotely be considered a threat. She had seen him take out common criminals, Servants, vampires and other monsters. However, that paled in comparison to seeing Puncher fight the Dead Apostle Ancestors. Rin involuntarily shuddered when she recalled how Puncher had destroyed half of Primate Murder's body with one half-hearted punch. And later on he had topped even that by killing the TYPE Mercury, a being that did not actually have a concept of death and was thus unkillable for humans.

And then Puncher had killed it with one blow.

'His strength makes no fucking sense!' Rin raged internally, holding back the urge to rip out her hair in frustration. 'It's like whenever he punches something the world goes "fuck it" and explodes! How is that possible?!'

Rin would have continued her internal rant a bit longer if she hadn't been interrupted by the sound of the door to the roof opening. When she turned around she came face to face with a person she currently held many conflicting feelings for: Emiya Shirou.

On the one hand she had always been a little curious about the red haired boy. However, now that feeling was overshadowed by the fact that this relatively insignificant boy had somehow turned into her Servant. One part of her was so curious that she wanted to lock him up in her basement and study him in detail to uncover his secret, but that same part also suggested several tools that were definitely not used for research of any scientific kind, so Rin wisely decided to ignore that part of her. The other part simply wanted to grab the boy by his throat and shake him until she felt better about all that nonsensical shit her Servant had been putting her through ever since his appearance. Rin was quite sure that she would feel better after this than after trying it on her own Servant – again. The one time she had tried it on the day she had met her Servant, Puncher had merely patted her head as if she was a little puppy biting his ankles! ... Which was probably true for him.

Anyway! When Rin saw Shirou enter the roof, she saw something familiar: rings under the eyes. In a moment of pity, Rin decided to put her own troubles aside for a moment and offered a simple "Long night?" to the boy.

Shirou raised his head and blushed a little, making Rin raise an eyebrow. That was new...

"You could say that," Shirou replied after a moment. "I apparently have gone crazy and have the voice of a blue haired man in a jumpsuit in my head. Not only does he want me to drink booze and seduce my caretaker, no, he also makes inappropriate comments about every girl I come across and wants me to show them my 'Great Bulge' or something like that. And the only reason I am telling this to you instead of a licensed psychiatrist is because the voice insists that you'd actually understand all this."

Shirou's eyes revealed that he clearly doubted this and was quite close to a nervous breakdown. Now, normally Rin would have walked away and stayed far away from Shirou after hearing such a story. But the fact that he mentioned a blue haired man in a jumpsuit was too much of a coincidence.

Rin felt her still lingering headache version. This was definitely Puncher's fault somehow.

"... alright, Emiya-kun, let's meet at your home today after school. I think we have a lot to talk about."

And did they ever!

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[In the evening]

"I KNEW IT! IT'S ALL YOUR DAMN FAULT, PUNCHER!"

Rin's voice echoed across the Emiya estate and scared away all local wildlife quite efficiently.

The Servant in question blinked in confusion. "... you lost me."

The right eye of his Master started to twitch. Rin then pointed at Shirou, who was lying on the ground without his shirt on and looked both embarrassed and confused. The talk about magecraft had been revealing enough, but then Rin had insisted to check some injuries she had apparently healed yesterday. That had been when the screaming had started. "I didn't really check yesterday, seeing how I was too busy healing Emiya-kun after you smashed his ribcage with the content of another smashed ribcage! But now that I had a moment to take an actual look I discovered that this isn't Emiya-kun's original heart in his chest!"

"Wait, what?!" Shirou yelped in surprise.

Puncher scratched his cheek. "... then what IS in his chest?"

"IT'S LANCER'S HEART YOU MORON! YOU KNOCKED A SERVANT'S HEART INTO THE CHEST OF AN UNINVOLVED BYSTANDER!"

Her Servant did not really see the problem. "Well, what's the problem? As long as something keeps pumping blood through his body everything's fine, right?"

A voice only Shirou could hear commented that with a quite angry voice. "Oh yeah, of course YOU would think like that..."

Oh how Rin wished to beat in her Servant's head with something. "The problem, you idiot, is that this is just. Not. Possible! You can't just craft parts of a Servant onto a human, heck, even if I used a part of you to attach to Emiya there would be problems, and you're his future self."

"... come again?" Shirou was once again ignored in favor of Rin ranting at Puncher.

"By the Root, nothing of this makes sense! It's like whatever you punch just forgets the rules of existence! It's like you punch something and suddenly gravity stops working! And now Emiya over here is haunted by the spirit of a spirit, because I accidentally did a heart transplant, which makes even less sense! How! How does one get so strong that he literally makes the world go cuckoo by swinging his fists?!"

However, most of this simply went over Puncher's head. "Well, that does remind me of the one time I threw rubble into the air and it didn't come down for an hour. I just thought I threw it really high. Or the one time I jumped from the moon back to Earth after that one guy knocked me into it."

"I asked you a damn question!" Rin was sorely tempted to shoot some curses at her Servant, but she knew that it wouldn't do anything. She had tried before.

"I'd also like to know," Shirou added from his position on the ground, although by now he had sat up again. "I didn't really get all of that, but... she said you're me from the future, right? And you're a hero? So tell me, how do I get strong enough to be a hero like you?"

Puncher looked at Rin and his past self. Alternate self. Original self? 'Yeah, that stuff is still confusing as hell.'

"You want to know how I got so strong? Well, I don't mind telling you, but I can already tell you that you might not like my answer. When I told the Rin of my time... timeline... dimension? Anyway, when I told my sister-in-law, she accused me of lying."

Shirou blinked. "You have a sister, Tousaka-san?"

Rin barely registered Shirou's question and answered on auto-pilot. "Yeah, Sakura is my sister, you should know her."

And then her brain registered what her mouth had just blurted out.

Shirou's mouth dropped open. "Sakura is your sister? And I married her?"

"YES!"

All four people in the room (well, two people, one Servant and Lancer's ghost) turned around when they heard a new voice. The next moment Shirou was tackled by one Matou Sakura who had jumped at him from the door five meters away – without taking a run-up. All of Shirou's reactions to this were then shoved aside by Sakura's tongue as she invaded her beloved Sempai's mouth.

"Ah, at least Sakura never changes." Puncher said fondly as he watched Sakura greet Shirou as she did with him most of the time.

The familiar tone of Puncher's voice made Sakura look up from a thoroughly dazed Shirou. When she saw the Servant, her mind went blank.

"Two sempais?"

With that Sakura promptly fainted, a happy smile on her face and blood running from her nose.

And Rin's headache once again got worse.

"Well," Puncher began. "Where were we again?"

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

A few days had passed since Puncher had revealed his heroic workout program to Shirou and gotten his alternate/past/original self started on training. The boy was very eager to try it out, and encouraged by Sakura (who had promptly moved into the Emiya residence) and Lancer's not so helpful comments, Shirou was destined to become a hero in the future. Thus this Shirou never became a Master, although he did sort of share Rider with Sakura. At first he had not been sure about him and Sakura, but those doubts quickly disappeared when Puncher took Sakura aside and told her how his Sakura had won him over easily. As it turned out, for a man like Shirou, who loved to cook, nothing was sexier than a woman in nothing but an apron. Go figure.

There had also been some problems with Sakura's family, and especially Shnji, but those had mysteriously gotten solved before Shirou could even visit their home to talk things out. Strangely enough Shirou also hadn't seen Shinji at school since that day.

Shirou also still had Lancer's voice in his head, and as much as he hated to admit it, he was starting to influence him. He had tried to fight it, but...

~Flashback~

"A hero can't act like that!" Shirou argued as Lancer once again tried to convince him to drink large amounts of alcohol before engaging in battle or sex, possibly both with the same person. He certainly had eyed Rider in an appraising way.

Lancer only laughed. "Kid, you do realize I AM a hero and can therefore be not wrong about that? I am a well known hero, so the way I act is how a hero acts."

Shirou had no real answer to that. "... you have a point there"

~End Flashback~

Ever since then Shirou had become more and more outgoing in his heroics, much to the joy of the girls sharing his home.

As for Puncher...

"... you broke the Holy Grail." Rin said flatly.

"In my defense, I had no idea my punch would hit the Grail." Puncher argued.

"You destroyed the entire mountain of the Ryuudou Temple. Where the Holy Grail was under."

"As I said, if someone had told me that the Holy Grail was under that mountain, I wouldn't have knocked Caster's dragon into it like that."

Rin grimaced. That had been a horrible sight. Apparently Puncher had pushed Caster so far that she had decided to summon a dragon she couldn't even properly control. It probably had to do with the fact that Puncher had taken out Saber and Assassin with only one punch – as he had the dragon and Caster later on. Puncher had also told Rin that originally Caster hadn't even known how to summon a dragon, but apparently Puncher's presence had once again sent the rules of the universe home crying, and thus it had SOMEHOW worked. That (probably) also explained why the strain caused by the Servants on the Masters for maintaining them had not increased despite no Grail doing the heavy lifting for them.

"I'm still not sure how that fake priest managed to convince everyone that the dragon was a movie prop..." Rin muttered to herself. When she saw that Puncher was about to leave her house again, she spoke up. "Where are you going now? Saber, Lancer, Caster and Assassin are dead, Rider is doing god knows what with Sakura and Shirou, and I doubt Berserker is any challenge for you either. Their Master would have to be downright suicidal to challenge you, and I doubt they didn't see you one-shotting that dragon barehanded."

"Ah, about that," Puncher began. "I actually did get challenged by Berserker's Master."

Rin's eyes almost popped out of their sockets. "What kind of Servant do they have to challenge YOU?! You sent a dragon through a mountain with a single punch. Who can possibly defeat you?"

Puncher's expression was surprisingly serious. "Rin. I am actually not sure I can defeat this opponent. I have trained hard last night, but my skills might not be a match for her. I have seen her gamer score, she's really good."

And like that, any tension in the room disappeared like any opponent hit by Puncher's fist.

"... you got challenged by Berserker's Master to play a videogame? That's it?"

"Yes. We also have a favor riding on it as bet, so naturally I must do my best. Wish me luck!"

With his cape fluttering in the wind, Puncher disappeared.

Rin looked at the spot where her Servant had disappeared for a few more seconds before she turned around and went to her room. A part of her just wanted to cry, but she had come to realize that the best way to deal with her Servant and anything related to him by simply ignoring it. If she had to experience any more of the stuff that happened around Puncher she might end like Shirou and join him in his crazy.

Rin shuddered at that thought. There was a reason she kept that cursed Kaleido-Stick locked up in the basement.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[Meanwhile...]

In the castle of the Einzbern family, a fierce battle took place. Fists impacted, weapons clashed, and blood was spilled. And in the end...

"Yay, I won! Suck it nii-san, that's ten wins in a row for me!"

In the face of Illyasviel von Einzbern's gloating, all that Puncher could do was sulk. He actually liked playing videogames nowadays as it was a nice way to pass time between short battles against monsters and eldritch abominations, but frankly, he sucked at them.

"Alright, you won, no reason to rub it in... Like you did when you kept punching me for ten more minutes after I already died with that infinite combo."

The girl's smugness did not decrease the slightest, and Shirou sighed. "Well, you won our bet, so what do you want me to do?"

Illya's smirk became downright evil. She had learned quite a bit in the past few days and was eager to put that knowledge to use.

"You see, nii-san, there's actually some... family business I need your help with back in Germany..."

Puncher raised an eyebrow. At the same time, hundreds of miles away, Jubstacheit von Einzbern felt a chill run down his spine.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

While Shirou and Illya were busy in Germany... reconnecting with their estranged family, another important meeting took place back in Fuyuki City, more specifically, in a certain church on a certain hill. Kotomine Kirei, priest, former and current Master and contender for the position of most twisted person to ever walk the Earth was currently speaking to Gilgamesh, the Servant Archer of the previous Holy Grail War.

However, the King of Heroes was not his usual arrogant self. He wasn't even commenting on Kirei not providing any entertainment or that 'his' Saber had been defeated already. All of this made it clear that something serious was going on.

"What is the matter, King of Heroes? Could it be that you are scared of the Servant who has defeated all the other Servants so far?"

Gilgamesh did not react to Kirei's slightly mocking tone, yet another sign for the priest that the situation was dire. "Don't be a fool, Kotomine. I have no reason to fear anyone. However, this person who has been summoned by the Grail... after seeing him fight that little dragon my theories have been confirmed. He has performed the Ancient Babylonian Workout!"

Despite Gilgamesh's grandiose announcement, Kirei merely raised an eyebrow. "' Ancient Babylonian Workout'? I am afraid I am not familiar with that term."

"Pff, of course not. Humanity has long since forgotten the ways to acquire true strength! And while I am confident in my treasures, I must not underestimate someone who can fight on the level of my true subjects. Indeed, there is only one thing I must do now. I must retrain myself to my former glory!"

The king turned towards Kirei. "Kotomine! Close the church for a week, I will be using one of my most prized Noble Phantasms, one that was created when I first started fighting alongside my one true friend Enkidu!"

"Oh?" Kirei was a little intrigued by this. "And what would be the name of this Noble Phantasm?"

"In my infinite mercy, I shall enlighten you. It's the original Training Montage, 'Shutur Eli Sharri'!"

Kirei allowed a small smirk to appear on his lips. "Very well then, oh King of Heroes. I shall leave you to your training."

The priest turned around to leave, but the moment he did so he found himself wrapped up by the chains of Gilgamesh's Noble Phantasm 'Enkidu'.

"Where are you going, Kotomine? This Noble Phantasm of mine was created when Enkidu and I worked together, as such it is the most effective when done by two people. And while you are but a poor substitute, I shall make do with what I have. Now, prepare yourself!"

After the first week Kirei discovered that he was actually capable of feeling joy from his own misery. It made the hell he went through a little more bearable, but after the second week even that didn't help anymore.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[Two weeks after Puncher and Illya's trip to Germany...]

Illya and Puncher returned from their impromptu journey to their extended family and were quite happy. As with many family reunions, that had been quite some tears involved, and even a party. But to be fair, the tear had been part of a 'blood and tears' package and the party had been thrown by the few survivors that Illya had graciously spared when the pseudo-siblings had finally left.

"That was nice, nii-san, we should do that again sometime." Illya said with a big satisfied smile on her face.

"Meh, it was kind of boring most of the time. You'd think an old family like that had some super-weapons lying around in a sealed off basement or something."

"Halt!"

Before the duo could continue their trip back to their respective residences, they were interrupted by a regal voice calling out to them. They turned around and came face to face with... well...

There was no real way of describing it.

For one, music had started to play. It vaguely made Puncher think of a stone mask and muscle-bound super vampires from ancient times. Well, the muscle-bound thing might come from the fact that they were being approached by two very muscular guys wearing barely more than loincloths. At least the blonde one had some sort of robe for his lower body.

Puncher faced the incoming duo (and music) with a blank faced honed from many, many weird encounters that left him kind of desensitized to everything people considered strange.

When the strange newcomers finally arrived before them and struck a pose, the dark haired one knelt down next to the blonde one, who began to speak.

"Greetings, Servant. I am Gilgamesh, the King of Heroes, and I have judged you worthy of being my opponent!"

While Illya was too perplexed to react in any way, Puncher had experience with stuff like that. "... yo. My name's Shirou, but I currently go with Puncher. Nice to meet you...? You look familiar. But I think I remember you with way less muscles..."

Gilgamesh and Kirei struck another pose. "It is indeed possible we met in another battle across time and space before! However! If I was defeated by you, I must have been weakened by summoned as a mere copy of my true glorious self! I have recognized your strength and thus regained my true power by performing the Ancient Babylonian Workout with the help of my training montage Noble Phantasm!"

Puncher raised an eyebrow. "I heard that name before... it's like my workout of 100 push-ups, 100 sit-ups, 100 squats and 10km running. Every. Single. Day. Right?"

The King of Heroes nodded. "Indeed! And now that I have found an opponent worthy of being crushed by me, we shall engage in a fight to the death! Your death of course!"

"Okay. See you in a bit in that park over there."

And with that Shirou took a still stunned Illya by the hand and lead her back to her castle, leaving behind a slightly surprised Gilgamesh and Kirei, who decided to strike some more poses before heading to the park. It wasn't like they were in a hurry after two weeks.

On his way to the park Puncher stopped by Rin to let her know what he was going to do.

"Hey Rin."

Rin promptly spat out the tea she had been drinking when Puncher appeared in her house without a warning. "Wha – Puncher! You're back! Where were you the last two weeks?!"

"Yeah, when I lost that bet with Illya she dragged me to Germany for two weeks. Also, I'm going out to fight this guy called Giga-something and his muscle priest buddy. See you later."

And then he was gone again.

Rin's brain desperately latched onto the last part of the conversation to make at least some sense of what had just happened.

"... muscle priest? I think there's only one priest in the entire city. He couldn't be talking about...?"

Forgetting about her spilled tea, Rin grabbed her jacket and ran out of her house to follow Puncher. She didn't know what he was going to do, but she was sure it would involve a lot of collateral damage – again.

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

When Rin finally caught up with her Servant (by following the sound of explosions and things breaking), Rin arrived to the end of what must have been an epic battle. Puncher's outfit actually looked slightly torn and dirtied in some places, and it was also clear that his opponent had actually managed to survive Puncher's, well, punch.

"Oh, hello Rin. How nice of you to join us."

The young magus whipped her head around when she heard a very familiar voice from next to her. But any answer she had died on her lips the moment she actually saw Kirei. The fake priest had turned into a wall of muscles, and the loincloth he wore did not leave much to imagination.

Turning red in embarrassment, Rin covered her eyes with an indignant shout. "Kirei! What the hell happened to you?!"

The man in question merely chuckled. "I was forced to live through hell... but not only did it bestow me with this incredible body, no, it also allowed me to gain new insights into the realm of suffering! I was so blind – why only cause pain and misery in others? I had simply not yet tasted the absolute hell an individual could go through!" He struck a pose. "I have been reborn in the fires of hell! Yes, from this day on, I shall-"

Whatever his great announcement was, it was cut short when Gilgamesh partially blocked an attack from Puncher and its remaining force hit Kirei like a high-speed train, liberating his head from his body. If Rin hadn't already seen worse from Puncher's memories, she might have been shocked by the sight. As it was, however, she merely shifted her attention to the two who were still fighting.

"Haha, you are indeed strong, Puncher! However, as the one true King," Rin swore she could hear the capital letter, "I cannot allow myself to be defeated! Take this, the ultimate attack of my most powerful weapon!"

A golden ripple spread behind Gilgamesh, and a strange cylindrical sword appeared, which was swiftly grabbed by the blonde.

"Now, awaken, Ea! A worthy opponent has appeared!"

Rin broke out in cold sweat when she felt the power this new weapon was giving off.

"Disappear! Enuma Elish!"

With a mighty thrust of his weapon, Gilgamesh launched a beam of pure destruction at Puncher, who faced it head on.

"Very well... then I shall also use my ultimate attack."

The white haired hero simply pulled back his fist to face the incoming red energy attack.

"Super Move: Serious Series – Serious Punch!"

It should not be possible to counter an attack that created a rift in time and space with a punch.

Puncher did it anyhow.

The force of his punch caused a clash of two unstoppable forces to grind against each other. At the side, Rin had long since retreated to a safer distance, but even that did not help her as the two forces continued to fight for supremacy. The two attacks caused a bright light to shine, and eventually Rin was forced to close and avert her eyes, the noise steadily growing louder in the background.

And then – nothing.

Rin carefully opened her eyes and looked around. She saw nothing. As in, NOTHING. No ground, no trees, no city! She was floating in a void of indescribable color. Next to her were Puncher and Gilgamesh, who looked around with the same expression of confusion.

It was actually Rin who first regained enough of her wit to ask the question on everyone's mind. "Okay... so what happened?"

Silence followed. Then, after a while, Gilgamesh reluctantly answered.

"I think... we broke reality."

"Yeah, probably." Puncher agreed pretty nonchalantly.

"... I'm sorry, WHAT?!" Rin shouted. "How do you even do that?! And why am I here then? I can understand you two freaks somehow managing, even if it's just through sheer dumb luck, but why me?!"

Puncher shrugged. "Well, you're still my Master... maybe you got dragged along?"

"I... don't even know what to say anymore." Rin's voice spoke of incredible mental exhaustion. "So? What do we do now?"

"Well," Puncher began before Gilgamesh could say anything. "If a punch broke reality... maybe another will recreate it?"

Rin's mouth opened and closed. Then she opened it again, only to say nothing once more.

"Why do I even still bother...? You know what? Screw this. I'll just float over here while you do your thing. I have run out of care for anything."

As she floated away, Puncher exchanged a look with Gilgamesh. Both shrugged a little helplessly.

"Well, no time like the present."

And with that Puncher once again pulled back his fist...

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

[A little later...]

"Hmm..."

Emiya Shirou felt as if he had just missed something incredibly important.

"What's wrong, darling?"

Shirou turned around and came face to face with his loving wife Sakura.

"It's nothing, Sakura, just had a feeling of déjà vu or something."

From the kitchen another voice could be heard. "Hurry up and kick some ass, kid, are you a hero or a what?"

Shirou rolled his eyes but had a smile on his face. "Yes Lancer-sensei. See you later. And you too, Sakura."

After a quick goodbye kiss, Shirou put on his cape and set out for F-City where a monster had been sighted. A hero's work was never done after all!

At the same time, a few miles away, Tousaka Rin, Puncher and Gilgamesh stared at a giant building that was apparently the HQ of the so-called "Hero Association". In the distance they could see a giant bird monster attacking a skyscraper, and even further away a dinosaur walked through a wasteland.

Rin turned towards Puncher.

"Just so you know... I blame you for this."

Her Servant could only shrug with his shoulders, feeling a little embarrassed. "I honestly had no idea that would happen."

"Sorry to interrupt, but..." Gilgamesh chimed in. "But do you guys have a place to stay? I think the church I used to live in just got destroyed up by a monster made of seaweed."

Rin's head dropped in defeat.

"What did I do to deserve this...?"

[OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS][OPS]

And beyond conventional time and space... Zelretch laughed, happily digging into his bowl of popcorn. He knew this would be a great idea

The End

(For real this time.)

**Notes for the Chapter:**

> And as I promised, here is some information about the more serious crossover. Also, if any of you are interested and want to write a story with this, feel free to do so, just tell me beforehand. Anyway, here's the set-up:
> 
> When the Holy Grail spilled its content at the end of the 4th Holy Grail War, the essence of Angra Mainyu went deep into the Earth. Its curse managed to reach even Gaia and Alaya and began to corrupt them. In order to prevent total contamination, the two great wills exorcised the corruption from themselves, but it then began to turn into a 3rd personality that had aspects of both Gaia and Alaya - a part of humanity and nature that craves only destruction.
> 
> As such monsters from both human and animalistic origin began to spread over the last 10 years, their appearances always centered around Japan, where the taint is the strongest. Their aim is always the destruction of either mankind or the planet itself.
> 
> To combat the growing thread of Angra Mainyu, Gaia and Alaya began creating and empowering their own agents. While Gaia tried to eliminate the creations of Angra Mainyu and mankind with the help of beings like Vaccineman, Alaya chose to select individuals with potential and empowered them, creating the so-called "Super Heroes".
> 
> The reason why Alaya and Gaia are more active now is because of the threat Angra Mainyu poses and that both wills have by now the strength to directly confront problems. Due to the many deaths caused by those disasters, Alaya also has more power for humanity to spare, but instead of empowering everyone, like it did in Gilgamesh's time, it chooses a select few and empowers them immensely. Also, alongside powerful fighters and technology users, Magic Heroes are also a thing as magecraft has become public knowledge again. With humanity being in constant danger, the Clock Tower no longer had the option of hiding in secrecy.
> 
> The story can go many ways from there. The Holy Grail War can still take place, or it can be long since over. Shirou can already be an active hero and/or become Saitama's second disciple after meeting him.
> 
> And that's it for this story, for real this time. Well, I might make an announcement if I ever get around writing this other story. But there'll be no more chapters about Shirou one-punching everyone and everything. If you have any question about what happened in this chapter, feel free to write me a PM, I'll answer them for sure.
> 
> Well then, see you around and Merry Christmas / Happy Holidays to you all!
> 
> Sir Godot

**Author's Note:**

> And that about wraps things up. I could have continued the story like this, but not for long as I would have run out of enemies for Shirou soon. Needless to say, the upcoming multi-chapter story will concentrate on characters from both series, so you can expand a bigger plot and actual battles.
> 
> I'd like to thank kyugan, sketchfan and The Infamous Man at this point for helping me with some of the planning, you guys rock.
> 
> If you liked this story, please leave a short review. Any feedback you give will be useful for the pseudo-sequel I talked about earlier. That aside, I hope you enjoyed the story.
> 
> So long,  
> Sir Godot


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